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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

Is Antarctica losing or gaining ice?

What the science says...

Satellites measure Antarctica is gaining sea ice but losing land ice at an accelerating rate which has implications for sea level rise.

Climate Myth...

Antarctica is gaining ice
"[Ice] is expanding in much of Antarctica, contrary to the widespread public belief that global warming is melting the continental ice cap." (Greg Roberts, The Australian)

Update Nov. 7 2015

A study published by Jay Zwally and his team on Oct. 30 (Zwally et al. 2015) has suggested that until 2008 there might have been a bigger increase in ice on East Antarctica than there is a decrease in the west, meaning that total Antarctic land ice is increasing. While their results for the Antarctic Peninsula and much of West Antarctica agree with other research, the study disagrees with many other techniques. We will update this discussion once more studies address this issue. Until then here are links to some recently published takes on the study:

Skeptic arguments that Antarctica is gaining ice frequently hinge on an error of omission, namely ignoring the difference between land ice and sea ice.

In glaciology and particularly with respect to Antarctic ice, not all things are created equal. Let us consider the following differences. Antarctic land ice is the ice which has accumulated over thousands of years on the Antarctica landmass itself through snowfall. This land ice therefore is actually stored ocean water that once fell as precipitation. Sea ice in Antarctica is quite different as it is ice which forms in salt water primarily during the winter months. When land ice melts and flows into the oceans global sea levels rise on average; when sea ice melts sea levels do not change measurably.

In Antarctica, sea ice grows quite extensively during winter but nearly completely melts away during the summer (Figure 1). That is where the important difference between Antarctic and Arctic sea ice exists as much of the Arctic's sea ice lasts all the year round. During the winter months it increases and before decreasing during the summer months, but an ice cover does in fact remain in the North which includes quite a bit of ice from previous years (Figure 1). Essentially Arctic sea ice is more important for the earth's energy balance because when it increasingly melts, more sunlight is absorbed by the oceans whereas Antarctic sea ice normally melts each summer leaving the earth's energy balance largely unchanged.Figure 1: Coverage of sea ice in both the Arctic (Top) and Antarctica (Bottom) for both summer minimums and winter maximums Source: National Snow and Ice Data Center

One must also be careful how you interpret trends in Antarctic sea ice. Currently this ice is increasing overall and has been for years but is this the smoking gun against climate change?Not quite. Antarctic sea ice is gaining because of many different reasons but the most accepted recent explanations are listed below:

i) Ozone levels over Antarctica have dropped causing stratospheric cooling and increasing winds which lead to more areas of open water that can be frozen (Gillet 2003, Thompson 2002, Turner 2009).

and

ii) The Southern Ocean is freshening because of increased rain and snowfall as well as an increase in meltwater coming from the edges of Antarctica's land ice (Zhang 2007, Bintanga et al. 2013). Together, these change the composition of the different layers in the ocean there causing less mixing between warm and cold layers and thus less melted sea and coastal land ice.

All the sea ice talk aside, it is quite clear that really when it comes to Antarctic ice and sea levels, sea ice is not the most important thing to measure. In Antarctica, the largest and most important ice mass is the land ice of the West Antarctic and East Antarctic ice sheets.

Estimates of recent changes in Antarctic land ice (Figure 2, bottom panel) show an increasing contribution to sea level with time, although not as fast a rate or acceleration as Greenland. Between 1992 and 2011, the Antarctic Ice Sheets overall lost 1350 giga-tonnes (Gt) or 1,350,000,000,000 tonnes into the oceans, at an average rate of 70 Gt per year (Gt/yr). Because a reduction in mass of 360 Gt/year represents an annual global-average sea level rise of 1 mm, these estimates equate to an increase in global-average sea levels by 0.19 mm/yr.

There is variation between regions within Antarctica (Figure 2, top panel), with the West Antarctic Ice Sheet and the Antarctic Peninsula Ice Sheet losing ice mass, and with an increasing rate. The East Antarctic Ice Sheet is growing slightly over this period but not enough to offset the other losses. There are of course uncertainties in the estimation methods but independent data from multiple measurement techniques (explained here) all show the same thing, Antarctica is losing land ice as a whole, and these losses are accelerating quickly.

Comments

I suspect the "water lift" effect might come to dominate in coming years. The underside of the ice shelfs slope upward from their grounding line to the seaward edge of the ice. As this ceiling melts under the influence of slightly warmed sea water, it freshens the water which being lighter, flows oceanward along this upsloping ceiling of ice. As the grounding line becomes deeper and deeper as the ice melts back under a retrograde slope of the ocean bottom, this effect should increase. Of course as the freshened water flows up and out on the surface of the ocean, it pulls sea water in under the ice. An added effect is that the ice melts at lower temperatures at depth so the fresher water may be "super cooled" with respect to the shallow water where it exits the ice shelf. This could be an added explanation for the increase in sea ice as this very cold, somewhat fresher water then comes in contact with Antarctic Night air. These currents may also be pushing the ice outward, opening leads that then freeze over.

A study published by Jay Zwally and his team on Oct. 30 (Zwally et al. 2015) has suggested that until 2008 there might have been a bigger increase in ice on East Antarctica than there is a decrease in the west, meaning that total Antarctic land ice is increasing."

There is nothing in that study to suggest that he ice gain that has been occurring for 10,000 years has stopped.

The Science has shown that Antarctica is gaining ice. Clinging to this false claim that the "science says" Antarctica is losing land ice shows poor alligiance to science.

There are a whole bunch of studies that show the Antarctic (land-based) ice sheet is losing mass versus Zwally's study that claims otherwise. Zwally's work is currently incompatible with Holocene sea level history and recent assessments of the sea level budget.

So there's a considerable volume of scientific work arguing against it. We'll just have to wait and see if Zwally's work stands up to scrutiny. If it does, we will change the text accordingly. Changing it now would be premature.

As for Antarctic sea ice, that's very interesting and very likely related to the wind trends and their effect on the polar gyres. SkS will have a new post on that in a few weeks.

That Zwally paper is interesting. Set aside the matter of the total mass change for a moment, and look at the changes between 1992-2001 and 2003-2008, the delta column in Table 10 or by eyeball from Fig 9. Mass waste in PIG, Thwaites and neighbours had doubled in the periods covered in the paper, the you can see the hole burning toward Ross, Ronne and the Transantarctic mountains. Recall that we are now in 2016. So apart from an overall constant, the trends agree. Fig 9 indicates that Totten is another place to watch, and I am glad the Amery doesn't seem to be waking up, at least in this data.

Maybe someone could help me understand. Antarctic ice? If the land ice is melting but the sea ice is increasing, don't we have two separate causes? It don't understand how you can have both with the same environment.

Anecdote: When the glacier covered Maine the plate was 200 feet below sea level. The glacier melted away ( from global warming?? ) and the land plate floated up and is now 4 feet above sea level. Or did the sea level fall because the land mass moved up. I am sure someone out there could explain this to me. please!

It seems to me when a tectonic plate looses massive amounts of weight ( ice ) in this case, it makes sense that it might move up because it is floating on magma ( or something like that ).

I also wonder about wind mills too. If our "climate" is dependent on air streams; based on earth rotation and adiabatic rise, then if we take the heat ( energy ) out of the wind we have not, will that not affect the wind currents driving our local climates?

Sea Ice has increased a little in the last few years although mainly at the maximum in winter. This year, at the summer minimum it is rather low. Drivers of sea ice extent? Possible changes in sea water salinity, changing the freezing point of the water. Changes in the winds around Antarctica, driving more spreading of the ice and freezing over of the open water created. The wind patterns may have changed due to a combination of the current Pacific Decadal Oscillation which has now started changing, and the ozone hole allowing more sunlight to reach the surface rather than being absorbed in the stratosphere; the extra energy from this may have accelerated the winds.

In Antarctica land ice doesn't melt much - it is too cold. Rather it flows slowly to the coast and eventually breaks off as icebergs. Factors changing this? Ice sheet breakup. Floating ice sheets (not seasonal sea ice) act as buttresses, slowing the speed with which land ice can flow. Some have broken up. Grounding line retreat. This applies particularly in West Antarctica where the 'land ice' is actually sitting on the sea floor 100's and even 1-2000 meters below sea level. Sea water intrusion at the grounding line is causing some retreat of the grounding line, so that ice that was grounded ends up floating, and easier for icebergs to break off. The key here is what is happening to sea water temperatures at the base of these sheets, 100's of meters down. This in turn can depend on differences in what is happening to different currents at different depths.

Some recent research also suggests there is a critical threshold wrt the height of ice cliffs. It seems ice when it contains cracks isn't strong enough to allow ice cliffs to rise much more than 100 meters above sea level. Otherwise it breaks off. Then buoyancy of the remaining submerged ice can then break that off from the main ice cap.

In reality, Arctic sea ice is at a record low and global sea ice is diminishing.

"Sea ice increases in Antarctica do not make up for the accelerated Arctic sea ice loss of the last decades, a new NASA study finds. As a whole, the planet has been shedding sea ice at an average annual rate of 13,500 square miles (35,000 square kilometers) since 1979, the equivalent of losing an area of sea ice larger than the state of Maryland every year."

“Even though Antarctic sea ice reached a new record maximum this past September, global sea ice is still decreasing,” said Claire Parkinson, author of the study and climate scientist at NASA’s Goddard Space Flight Center in Greenbelt, Md. “That’s because the decreases in Arctic sea ice far exceed the increases in Antarctic sea ice.”

“When I give public lectures or talk with random people interested in the topic, often somebody will say something in the order of ‘well, the ice is decreasing in the Arctic but it’s increasing in the Antarctic, so don’t they cancel out?’” Parkinson said. “The answer is no, they don’t cancel out.”

I have found this thread helpful to getting perspective on land and sea ice discussion. My comment is a question or request about data:

For a long time I have been trying to monitor land ice, but for the layman the information does not seem to be readily out there and updating regularly. I see this page:

https://climate.nasa.gov/vital-signs/land-ice/

However, that information has not been updated past March 2016. I've tried to dig around a bit for alterntaive sources of information and haven't so far been able to find any. I don't know if it is the function of this page to provide such information, but does anyone know of a good source that can readily be understood by non-scientists? (To get an updated reading of whether trends in Antarctica toward lower land ice are continuing).

Yes, I have been to nsidc.org a fair amount, particularly this page to try to understand each Northern Hemisphere summer what is going on with greenland ice melt:

http://nsidc.org/greenland-today/

While I do like that page, I must say I have not been able to find what I am looking for there, as far as clear non-scientist-oriented data that shows land ice changes over the years, whether for the Antarctic, Greenland or other places.

The NASA site I mentioned in my post above seems to show land ice mass changes.

There seems to be (as best I can make out) a common theme to both sources that they were satellite-based systems, with IceSat gone and GRACE no longer functioning fully, and both systems seem to have scheduled replacements. (Maybe I am confused and they are one and the same system, but it seems like possibly different systems and different planned replacements).

Perhaps it is the somewhat challenging nature of the science journalism involved, but I haven't seen a single news story which gets at the important question of how important this land ice data would seem to be, that no widely-disseminated information seems to be available dating past 14 months ago, and that both sources are dependent on expensive new planned launches which we can hope won't be pushed back or cancelled, but which are still 2-3 quarters away at the least.

Perhaps the IceBridge interim plane-based system can provide data, or perhaps other countries or systems are developing data? Japan? China? NASA has literally labeled this as a "vital sign" and it does seem important, so I'm hoping to uncover if there is more reliable data out there. Perhaps I have missed something at NSIDC. Do you have a specific link in mind?

It sounds to the outsider as though it is very important to you guys to say that the addition of ice in Antarctica is NOT due to global warming, a separate issue related to Ozone (are humans responsible for the Ozone hole?). But the loss of ice is due to global warming.

Seems to me addition of ice is a simple thing to say, and that attributing it to something else is kind of like saying this ice is different from that ice, that some ice counts toward the ice in Antarctica and some doesn't count.

And you sound awefully sure about that Ozone hole, Where are the references to the studies that prove lack of Ozone is the problem? Well, is there a problem that Ozone ice is messing up something in Antarctica? Should be plug the Ozone hole?

I think time has caught up with your comment "Let's just say Ice overall is growing in Antarctica, okay?" which is now twenty months out of date.

Overall, the Antarctic ice cap was certainly not "growing" ice-wise over the period 2002-16. (The Zwally theorising mentioned in the OP update is an interesting theory but nothing more.) And the Antarctic Sea Ice had been showing a slow rise in SIE over the satellite record 1978-2010 and then did show a dramatic upward wobble to early 2016. But since then, as the comment @463 pointed out, the drama has been in the opposite direction and now SIE continues lower than at any time earlier than 2016.

Part of your explanation for increasing ice in the Antarctic is that it's getting colder, and then you go on to say that it's actually getting warmer and that ice is decreasing, so which is it?

"i) Ozone levels over Antarctica have dropped causing stratospheric cooling and increasing winds which lead to more areas of open water that can be frozen (Gillet 2003, Thompson 2002, Turner 2009)."

"You're also correct in pointing out that snow accumulating in the East Antarctic interior is increasing, presumably due to increased precipitation caused by more humid conditions caused by warming air."

Response:

[JH] Please specify which "ice" you are referring to. Is it sea ice in the oceans surrounding the Antarctic continent, or is it glacial ice formed on the continent itself?

matt - as per JH comment, you need to take notice as to which ice you are talking about. Sea ice extent appears to be influenced by katabatic winds bring cold air from the interior over the surrounding sea. These increase outward dispersion of sea-ice was well as freezing the surface so you can increase seaice extent despite a warming ocean as per papers cited in article. The strength of the katabatic winds seems to be influenced by the ozone levels in the stratosphere. However, more observations are needed before this can established with certainity.

Land ice is a more complex picture. Early models (TAR I think), predicted Antarctic land ice would increase as warming seas resulted in more moisture being blown over Antarctica and falling as snow. However, this is balanced by substantial ice sheet losses on margins especially in West Antarctica as calving rates accelerate. You can see the pictures/videos of land ice mass change over here. Broadly it is mass gain around EAIS and mass loss of WAIS, with overall net mass loss.

I watch the video from years ago and giggle... "The unexpectedly rapid loss of land ice..." Assuming the maximum temps projected by the IPCC does this young man understand how long it would take for a even a 10% melt? Even during the most rapid ocean rise scenarios things will be just fine... The sky is not falling. How about helping the developing countries develop and solve an ongoing humanitarian crisis now that oh by the way is truly polluting the environment?

Response:

[TD] That video from "years ago" was made only 2.5 years ago. In my response to your previous comment I gave you a link to a Scientific American article that references studies from last year, which you could read if you were sincerely interested in learning. That "young man" in the video was a PhD candidate with a large number of peer reviewed professional publications directly relevant to the topic he was speaking about in that video. (A remarkable number of publications for a PhD student!) Now he is a postdoctoral fellow. His degrees and postdoc all are directly relevant: physical geography, geomatics, spatial analysis, glaciology, permafrost science, and northern environmental change.

Meanwhile you claim you are "working on" a PhD and have failed to respond to the specific counters to your claims that I already provided.

The percent of land ice melt is not relevant. What matters is the absolute amount of water released by the melt. Someone actually enrolled in a PhD program in planetary geology would know that.

Read the post about how much sea level will rise. After you read the Basic tabbed pane, read the Intermediate one. Watch the two videos. Then read professional statistician (multiple peer reviewed publications on climate change) Tamino's explanation of a new paper supporting the existence of sea level rise acceleration so much that by the year 2100 sea level would be .654 meters higher than in 2005, supporting the projections of IPCC AR5's RCP 8.5. Then explore the Surging Seas site to see the concrete, practical implications of that amount of rise, but keep in mind that the amount of rise could be double that .654 meters which was only extrapolated from observations up to now, because the current acceleration easily could increase. Then explore the US Geological Surveys site on sea level. If you really are enrolled in a PhD program, you should be able to handle the AR5 WG1's Chapter 13 on Sea Level Change. To learn about impacts, adaptation, and vulnerability, read WG2's report.

According to the most recent summary by the US Global Climate Change Research Program, the official report of the Trump administration, for sea level "A rise of as much as 8 feet by 2100 cannot be ruled out." That would cause a loss of more than a trillion dollars of real estate in Miami alone. World wide hundreds of millions of peoples homes would be washed away.

Your unsupported claim that " Even during the most rapid ocean rise scenarios things will be just fine..." is simply false.

According to the National Snow and Ice Data Center, the sea ice around Antarctica has set record lows each of the past two years. The land ice is declining at an increasig rate according to gravity measurements.

Hmm, if you are fixating on a outlier paper (Zwally 2015), then I suspect you are using extremely suspect sources for your information. Gravity and altimitry methods both have weaknesses (but different ones). A clever approach which reconciles the metholodies by a joint inversion of altmetry, gravity and GPS is Espanol et al 2016. Their approach demonstrates a sustained net mass loss of 84+/- 22 Gt/yr.

"How about helping the developing countries develop and solve an ongoing humanitarian crisis now that oh by the way is truly polluting the environment?" Why do you believe fixing climate (which is important way to help developing countries) is incompatiable with your perceived priorities?

Zwally et al 2015 took an unconventional approach to assessing the mass balance of Antarctica. Unlike other studies, before and since, that used satellite altimetry or satellite gravimetric methods, Zwally’s team chose to compare net snowfall accumulation to estimated ice discharge to the ocean. In order to do this type of analysis properly, 3 main things are needed:

1. It is critical to use the most optimal corrections for instrument biases (the ICESat data used need to have the appropriate saturation bias corrections to get real-world answers that are reproducible)2. The most-accurate densities of snow have to be used3. The most-optimal values for changes in bedrock elevation (GIA) in response to ice sheet mass changes have to be used

As has been since determined by multiple studies (A, B, C and D, listed following):

1. The ICESat bias corrections used by the Zwally team were appropriate for measuring sea ice, but not for measuring high altitude land-base ice sheets like found in Antarctica (the values returned for Lake Vostok alone were so unphysical that they should have made the entire study DOA)2. A value for snowfall density different than that determined by decades of land-based research was used3. The values used by the Zwally team to correct for GIA were too high by a factor of 2

As such, their results cannot be reproduced using well-established bias corrections, known snow densities and more appropriate values for GIA.

The values for the Antarctic ice sheet mass balance from NASA GRACE are the most current available (to January 2017). An ever-strengthening, consilient body of research using multiple methods all point to that conclusion.

Interestingly, previous research has shown that ice sheet mass contributions from land-based ice sheets have exceeded thermal expansion as the biggest contributor to global sea level rise. Recent research now has isolated the individual ice sheet contributions to global sea level rise.

Per Hsu and Velicogna 2017, between April 2002 and October 2014, the mass component of global mean sea level grew by about 1.8 millimeters per year, with 43 percent of the increased water mass coming from Greenland, 16 percent from Antarctica, and 30 percent from mountain glaciers. There is an additional ~1 mm per year of SLR coming from thermal expansion (H/T to Victor Zlotnicki).